Plancxtrai



J. ERICKSON.

MEASURED SERVICE TELEPHONE SYSTEM.

APPLICATION FILED JULY 20.1911.

1,312,688. Patented Aug. 12,1919.

Lfahn Erickson UNITED STATES PATENT OFFICE.

JOHN ERIGKSON, 0F GI-IICAG-O, ILLINOIS, ASSIGNOR TO AUTOMATIC ELECTRIC COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

MEASURED-SERVICE TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Aug. 12, 1919.

Application filed July 20, 1917. Serial No. 181,727.

To all whom it may concern:

Be it known that I, JOHN ERICKSON, a citizen of the United States of America, and a resident of Chicago, county of Cook, and State of Illinois, have invented certain new and useful Improvements in MBHSHIBCl-SBIV- ice Telephone Systems, of which the following is a specification.

My invention relates in general to measured service telephone systems and particularly to improvements in meter control circuits for automatic telephone systems. More specifically, the invention provides an improved system of control for substation meters which is well adapted for use in automatic party line telephone systems, and which involves a number of novel and highly useful features which will be pointed out and described hereinafter, reference being had to the accompanying drawings.

In the drawings, Figure 1 is a diagrammatic representation of the substation circuits in their preferred form, together with a fragmentary showing of certain exchange circuits, the latter bein included in order to assist in an understan ing of the operation of the substation. More in detail, the co1nplete substation is shown at the left of Fig. 1 and is indicated by the reference character A; the reference character C indicates a line switch or trunk selector at the exchange individual to the line of substation A; while the reference character E indicates an automatic connector switch. There is also shown in simple form a second substation A, the line of which is accessible to the connector E. Figs. 2 and 3 are circuit drawings showing modifications of the substation circuit shown in Fig. 1. Since my invention is not concerned with the mechanical construction of the meter itself, but rather with the circuits and with improvements in methods of operation and control, the mechanism has not been shown in detail; but the various parts and their relation are illustrated here in diagrammatically in approved manner, which in view of the advanced state of the art will be ample to enable one skilled therein to understand the invention.

Referring to Fig. 1, the substation A comprises the usual receiver 2, transmitter 3, switch hook 4, ringer 5, and condenser 6. Being an automatic substation there is also provided a calling device or impulse sender CD, of which only the impulse springs 7 and 8 and the shunt springs 9 and 10 are shown. This calling device is of the type in which the impulse springs are controlled by means of a finger hole dial to produce series of interruptions in the line circuit in accordance with the digits in a called number. Reference is had to the British patent to Dicker, #29554. of 1910.

In addition to the parts above enumerated there is provided a meter M, comprising an operating magnet 16 and a polarized con trolling relay 14; and a locking push button or key K, which controls the contact springs 21 to 25, inclusive and which is provided with an unlocking magnet 20. The meter M may be of the ordinary form, comprising a series of number wheels, which are adapted to register the total number of calls. The function of the key K will be explained fully hereinafter.

The two line conductors 30 and 31 extend to the exchange where they terminate referably in an individual line switch of which only the two line contacts are shown herein. The line switch C may be of any approved type and is operable u on the closure of the line circuit at the su station A to extend the line conductors 30 and 31 nto connection with a trunk line terminatmg in a numerical selector or connector switch, as the case may be, depending on the siz e of the exchange. For the sake of simplicity, no selector switches are shown in the drawing, it being assumed that the line switch C has direct access to a connector switch E, which in turn has access to a group of subscribers lines one of which is the line of substation A. The connector E, like the line switch C, may be of any approved two wire type, its most essential characteristic being the provision of means whereby upon the response of a called subscriber the incoming line conductors are reversed as regards their connection to the windings of the line or controlling relay. Thus in Fig. 1, the line conductors 30 and 31, before terminating in the windings of the line relay LR, pass through reversing springs on the back bridge relay BBR. Line, selector, and connector switches of suitable construction are shown in the U. S. Patent to Newforth, Reissue No. 13,901.

Having given a brief description of the apparatus, I will now proceed to explain the mode of operation, it being assumed for this purpose that the subscriber at substation A desires to establish connection with the subscriber at substation A. It is understood of course that the line comprising conductors 30 and 31 is a party lino, there being one or more other substations in addition to substation A connected in bridge of the line conductors. But since these substations may be all alike, at least in so far as the invention is concerned, only one of them has been shown. To proceed, upon the removal of the receiver at substation A, the transmitter and receiver are bridged across the line conductors as follows: conductor 30, switch hook springs 12 and 11, receiver 2, transmitter 3, conductor 33, contact springs 23 and 25 of key K, conductor 34, and impulse springs 7 and 8 of calling device CD to line conductor 31. The closure of the above circuit places the substation in condition for talking. The calling subscriber will now lace the receiver to his ear and listen for a ew moments in order to ascertain whether or not the line is in use. If he finds the line to be busy, he will replace the receiver and wait a reasonable length of time before again attempting to call. At least the subscribers are instructed to so roceed. Of course a calling subscriber w o finds the line busy can listen to the conversation going on if he wants to, but this does not PHJ'tlClL lar harm, for few subscribers will indulge in such a ractice, and I find that an arrangement of this kind is more satisfactory to the subscribers as a whole than a lockout system. However, any real attempt at interference, as by attempting to set up a connection while the line is in use, will result in charging an extra call to the interfering subscriber, as will ap ear later; and the knowled e of this fact wi 1 generally prove to be en cient inducement to insure against improper use of the line.

If we assume that the line is idle when the calling subscriber removes his receiver, the resultmg closure of the bridge at the substation will cause the line switch C to operate to extend the line conductors to the line re la of an idle connector switch, which we will assume to be the connector E. Having listened in the receiver and ascertained that the line is free, the subscriber may now proceed to complete the desired connection. Before operating the calling device, however, the push button K must be operated in order to remove the short circuit from the calling device sprin s 7 and 8. After being operated the pusi button is looked, that is, the spring 26 is held against return by the second notch in the end of armature 27. The actuation of the push button has the follow ing results: By the separation of springs 21 and 22 the short circuit is removed from the impulse springs (and 8 of the callin device; a circuit is prepared for the unloc 'ng magnet '20 at springs 24- and 25; and by the sc aration of springs 23 and 25 the polarized re ay 14- (until now short-circuited) is intro duccd in the bridge across the line. The relay 1-l is of low resistance, preferably about 4-0 or 50 ohms, and is shunted by the non-inductive resistance 1:) lo prrlnit the live passage of voice currents. Current flow over the line is now in such direction that the polarized relay is not operated to close its contact springs.

The calling subscriber may now proceed to operate the dial of the calling device CI) in accordance with the digits in the number of substation A, whereby the connector E is operated in the usual and well known manner to complete the desired connection, it bein assumed that the line of substation A is i le at the time. During the operation of the calling device the shunt springs f) and 10 are closed to short circuit that portion ol the substation bridge which includes the re ceiver transmitter, and polarized relay, this belng the usual provision made to reduce the resistance and impedance of the line circuit during the transmission of impulses.

When the called subscriber removes his receiver to answer the call, talking current is su plied to the substation A throu h the win ings of the back bridge relay BR. This relay is therefore energized to reverse the line conductors 30 and 31 as regards their connections to the windings of the line relay LR. Current now flows over the line circuit and through the polarized relay l t in reverse direction whereby the armature of the polarized relay is operated to close the contact springs 17 and 18. This operation prepares a circuit for the meter magnet 16. It will be observed that when once actuated the spring 17 is locked by the spring catch 19 so that the circuit of the magnet will be held closed independent of the called subscriber.

At the termination of the conversation both subscribers replace their receivers. When the receiver is hung up at substation A the meter magnet 16 is connected in bridge of the line as follows: line conductor 30, switch hook springs 12 and 13, conductor 35, contact springs 17 and 18. winding of magnet 16, and the impulse springs 7 and 8 to line conductor 31. Upon the closure of the above circuit the meter is actuated to register the call and at the same time the spring 19 is moved outward to release the sprin 17, thus openino the circuit of magnet 16. gimultaneous wit 1 the closure of the meter magnet circuit, a parallel circuit is closed through the unlockin magnet 20 as follows: conductor 35, winding of magnet 20, contact springs 24 and 25, and impulse springs 7 and 8 to conductor 31. When the magnet 20 is energized it attracts its armature 27 to release llU the push button K, and the circuit of the magnet is broken when the push button springs assume their normal position. All conductive bridges at the substation having been opened, the automatic switches at the exchange are released in the usual manner and restored to normal position.

It will be seen that the calling subscriber is forced to press the button K upon initiating the call in order to render the calling device operative and that this act also connects the polarized relay in the line circuit in readiness to prepare the meter circuit when. the called party answers. It Will be obvious that the reason for having the polarized relay normally out of circuit is to permit the calling subscriber to remove his receiver and listen to see if the line is busy without runnin the chance of having a call charged against him in case the line is found to be in use. It will be e ually clear that if a calling subscriber shoul operate the push button of his meter in an attempt to set up a connection, notwithstandin the fact that the line is already in use, e will be charged with an extra call. The current on the hue having been already reversed the polarized relay at the interferin subscribers station is operated as soon as the button is pressed, to prepare the meter circuit, and the fact that both subscribers must hang up their receivers before the connection can be released insures that the interfering subscribers meter will be operated as well as the meter of the subscriber first calling.

Inasmuch as in the ordinary two Wire system the line circuit must be opened for an appreciable interval to permit the switches to release, it mi ht occur to a subscriber, after havin dia ed a desired number, that the call coul d be secured free b jerkin the receiver hook down momentari y in or or to release the key K and cut out the polarized relay before the called arty had answered. To defeat an attempto this kind,the switch hook springs are adjusted so that springs 11 and 12 break some time before springs 12 and 13 make; and in addition the magnet 20 is made slow to energize by means of a slug of copper on one en of the core. With these rovisions, whenever the switch hook is held down long enough to enable magnet 20 to energize, the interval during which the line circuit is open is sufliciently long to cause the release of the switches.

Another device to prevent cheating by the subscriber is the provision of the, extra notch on the armature 27 of unlocking magnet 20. Without this arrangement the subscriber could operate the push button just far enough to separate the springs 21 and 22, without locking it however, and could then hold the button in this position while dialing the desired number, after which the button would be released and the polarized relay cut out of circuit. The successful issue 01: this method of securing a free call is prevented by placing two notches on the armature 27 and adjusting the push button as follows: When the button is pressed, springs 24 and 25 engage and springs 23 and 25 disengage before the end of spring 26 passes the first notch. Springs 21 and 22 are not separated, however, until spring 26 passes the first notch and shortly before it reaches the second, thus making it impossible to remove the short from the callin device without looking the push button, at least so far as the springs which control the polarized relay are concerned.

A brief explanation of the modifications shown in Figs. 2 and 3 will now be given. Referring first to Fig. 2, an inspection of the substation diagrammatically illustrated therein will show that it resembles the sub station in Fig. 1 very closely, the essential difference being in the construction. of the push button K and the arrangement oi circuits controlled thereby. The polarized rc lay 14 is not normally short circnitcd but is included in the line circuit directly the receiver is removed. Like in the substation shown in Fig, 1 the push button is provided to enable the calling subscriber to listen on the line without running the chance of having his polarized relay operate if the line should happen to be busy, but its mode of operation in performing this function is different. A high resistance 40 is provided, connected serially in the line circuit but normally short circuited by the springs of the push button. When initiating a call, the subscriber will press the button K before the receiver is taken ofi the hook and will hold the button in operated position While listening to ascertain the condition of the line. The resistance 40 is high enough to prevent the operation of relay 14 but does not prevent the subscriber from faintly hearing the conversation if the line is in use. In this case the receiver will of course be replaced before the button is released. If the line is found to be idle the push button is released without hanging up the receiver and the operation of calling the desired number is proceeded with. The meter M is operated when the calling subscriber hangs up at the end of a successful call as was described in the case of the meter M (Fig. 1).

The substation shown in Fig. 3 is very similar to the one shown in Fig. 2 and the operation by the subscriber is precisely the same. The difference lies in the particular means for operating the meter M The armature 41 of the meter magnet is normally locked in operated position by the latch 48. When a connection is established. and the called subscriber answers. the polar-- ized relay rotates the latch 43 far enough in release arn'iature 41 thereby closing springs -12 and permitting lever 44- to engage another tooth on the ratchet wheel of the meter. Now when the calling subscriber hangs up his receiver the meter is operated to register the call, as in the two :ases previously described; the circuit. of the meter is opened at springs 4-2; and the armature i1 is retained by the latch 13, being so held until released on the next successful call. The springs 42 are adjusted to break an instant before the latch 43 falls over the end of armature 41, and the latter is made comparatively heavy so that its inertia will enable it to complete its stroke.

l-Iaving described my invention what i consider to be new and desire to have protectcd by Letters Patent will he pointed out in the appended claims.

hat I claim as my invention is:

l. in a telephone substation, the combination with talking instrument-alitics and suitable circuits therefor, of a meter or call register a line circuit. means for closing said line circuit when a call is made, a relay and means for including it in the line circuit, means for preventing the subscriber from calling unless said relay is so included upon the initiation of a call, means for completing the connection to a called line, means for altering the current flow in the calling line upon the response of the called subscriber to operate said relay, a circuit for said meter prepared by said relay when operated, and means for closing said circuit to operate the meter when the calling subscriber replaces his receiver.

2. In a telephone substation, the combination with talking instrumentalities and suit able circuits therefore, of a meter or call register, a relay, a push button for including said relay in the line circuit, means for preventing the subscriber from calling unless said push button is operated upon the initiation of a call, means for completing the connection to a called line, means for altering the current flow in the calling line upon the response of the called subscriber to operate said relay, a circuit for said meter prepared by said relay when operated, and means for closing said circuit to operate the meter when the calling subscriber replaces his receiver.

3. In a telephone substation, the combination with talking instrumentalities and suitable circuits therefor, of a meter or call register, a relay, a normally inoperative calling mechanism, a device operable by the subscriber for rendering said mechanism operative and adapted to include said relay in the line circuit, means responsive to said mechanism for completing the connection to :1 called line, means for altering the current flow in the calling line upon the response of the called subscriber to operate said relay, a circuit Foy said meter prepared by said rclny when opcrulcd. and means for closingsuid circuit to opcrute the meter when the calling subscriber replaces his receiver.

-'l. in a telephone subr-atation, the combination with talking instrumcntalitics and suitulilc circuits lhcrclor. oi a meter or call registel'x a line circuit. a relay in said circuit normally inoperativ means For closing said line circuit, means For preventing the subscribe! from calling unless said relay is rendered operative upon the initiation of a call, means for completing the connection to a called line, means for altering the current How in the calling line upon the re spouse of the called uhscril'ier to operate said relay, a circuit F "aid meter prepared by said rcla" wh n operated, means for retaiuing said circuit in prepared condition indcpcndcul of mid relay, and means For closing :aaid circuit to operate the meter when the calling suhrlcriher replaces his rc- "eircr. i

5. in a telephone r zuhstatiou, the combination with talking iustrumentalities and suitable circuits therefor, of a meter or call register. a relay included in the line circuit normally inoperative when the line circuit is closed, means for preventing the subscriber from calling unless said relay is first rendered operative upon the initiation of a call, means for completing the connection to :2 called line, means for altering the current new in the calling line upon the response of the called subscriber to operate said relay, a circuit for said meter prepared by said relay when operated, means for closing said circuit to operate the meter when the calling sllbSClllJGI replaces his receiver, and means controlled by the meter for opening said circuit after the same has operated.

6. In a telephone substation, the combination with talking instrumentalities and suitable circuits therefor, of a meter or call register, a normally inoperative polarized re ay and. means for including it in the line circuit, means for preventing the subscriber from calling unless said relay is first rendered operative upon the initiation of a call, means for completing the connection to a called line, means for reversing the direction of current flow in the callin line upon the response of the called subscriber to operate said relay, a circuit for said meter prepared by said relay when operated, and means for closing said circuit to operate the meter when the calling subscriber replaces his receiver.

7. In a telephone system, a party line, subscribers stations on said line each provi ed with a measured service device, means for connecting said line in a talking circuit with a called line, means 'for causing a current flow in said party line characteristic of its busy as distinguished from its idle condition, a measured service device controlling magnet at each substation included in the line circuit and responsive to the said characteristic current flow therein, and means at each substation for rendering the associated relay unresponsive in order to permit the subscriber thereat to listen on the line to determine its idle or busy condition without Eharging himself with a call if the line is usy.

8. In a telephone system, a party line, subscribers stations on said line each provided with a meterin device, means for completing a talking circuit from said line to a called line, means for causing a current flow in said line characteristic of its busy as distinguished from its idle condition, a meter control magnet at each substation included in the line circuit when closed and responsive to characteristic current flow therein, and means at each substation for rendering the associated relay unresponsive in order to permit the subscriber thereat to listen on the line to determine its idle or bus condition without charging himself wit a call if the line is busy.

9. In a telephone substation, the combination with talking instrumentalities and suitable circuits therefor, of a meter or call register, a controlling magnet for said me ter nor-mall inoperative, a, calling device also normal y inoperative, and a two position hand operated locking device, the said device being provided with means which are operated in its first position to render the said magnet operative and with additional means operated in its second position to render the said calling device operative.

10. In a telephone substation, the combination with talking instrumentalities and suitable circuits therefor, of a measured service device, a controlling magnet for said device normally inoperative, circuit arrange ments such that the subscriber is prevented from calling unless said magnet is placed in operative condition upon the initiation of a call, and a mechanism for preventing the subscriber from restoring said magnet to inoperative condition after the connection has been established and before the called subscriber has answered.

11. In a telephone system, automatic switches for connecting a calling and called line, means responsive to the opening of the callin line for a definite time interval for releasing said switches, a measured service device and a self locking controllin mechanism at the substation on the calling line, an unlocking magnet for said mechanism energized when the receiver is hung u to open the line circuit, and devices for ma ing said magnet slow to energize, whereby the said switches are enabled to release before the said magnet has operated to unlock said mechanism.

Signed by me at Chicago, Cook county, Illinois, this 12th day of July, 1917.

JOHN ERIOKSON.

copies oi thin patent may be obtained for five cents each, by addressing the "Commissioner of Iatenta, Washington, D. 0. 

